Newborn Screening

Screening tests are laboratory tests that help to identify people with increased risk for a condition or disease before they have symptoms or even realize they may be at risk so that preventive measures can be taken. They are an important part of preventive health care.

Screening tests help detect disease in its earliest and most treatable stages. Therefore, they are most valuable when they are used to screen for diseases that are both serious and treatable, so that there is a benefit to detecting the disease before symptoms begin.

They should be sensitive - that is, able to correctly identify those individuals who have a given disease. Many routine tests performed at regular health exams are screening tests. Cholesterol testing and Pap smears for women are examples. Newborns are screened for a variety of conditions at birth.

A positive screening test often requires further testing with a more specific test. This is important in order to correctly exclude those individuals who do not have the given disease or to confirm a diagnosis.

A diagnostic test may be used for screening purposes, but a diagnostic test is generally used to confirm a diagnosis in someone who has signs, symptoms, or other evidence of a particular disease.

This article was last reviewed
on

June 7, 2017.

This article waslast modified
on December 6, 2018.

In the United States, routine evaluation of a newborn includes a number of laboratory tests. These tests are valuable because they have the potential to identify diseases and disorders before symptoms appear and before serious complications arise. Early detection allows treatment that may prevent development of serious health problems.

In addition to laboratory tests, a number of other evaluations are typically done to ensure the health of newborns. The article Newborn Care in the Delivery Room on the March of Dimes web site discusses some of the procedures that may be included in the first exam of a newborn.

Various conditions that may be present at birth (congenital) can affect the health and wellness of a newborn. Most of these conditions are rare, though some are more prevalent in certain families or ethnic groups. Disorders range from difficulties processing certain nutrients (metabolic), to problems with hormones (endocrine), to the production of abnormal forms of hemoglobin, the oxygen-carrying protein in red blood cells. Some of these conditions cannot be cured, but many can be managed so that the child can grow and live a relatively normal life.

Newborn screening tests help to identify potentially treatable or manageable congenital disorders within days of birth. Life-threatening health problems, mental retardation, and serious lifelong disabilities can be avoided or minimized if a condition is quickly identified and treated.

Newborns can be routinely screened for many of these disorders before leaving the hospital using a few drops of blood. Each state has its own newborn screening program, so the number of tests performed varies by state.

The Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC), part of the U.S. Department of Health and Human Services, recommends that all newborns be screened for 34 core disorders and 26 secondary disorders. The tests are organized into broad categories:

Physicians and parents may request a "supplemental newborn screening" panel in addition to the state-required tests. At some hospitals, you can indicate your preference for this more extensive testing when you check in for the birth. Supplemental newborn screening tests can also be arranged, in advance of the birth, through one of several private laboratories offering this service.

Reminders to parents:

Parents should also be aware that special collection techniques are used with newborns to minimize discomfort during specimen collection. In most cases, all the tests can be done using just a few drops of blood obtained from a pricked heel. Requesting supplemental tests will usually not require extra heelsticks or blood from your newborn.

Newborn screening tests are usually performed within 24 to 48 hours of life. For some tests, such as phenylketonuria (PKU) and congenital hypothyroidism (CH), it is important that they not be run too soon after birth. They may not accurately reflect whether a disorder is present if performed within the first 24 hours of life. Since women and their newborns may be discharged within a day or two of the birth, it is possible that a newborn could be tested with a sample taken within those first 24 hours. Consequently, some states routinely recommend screening two times, once in the hospital and then about 2 weeks later. This second screen is done to maximize the accuracy of testing.

The time it takes for test results varies by program. Generally, newborn screening results will be available within 10 to 14 days from the time the sample was taken. Ask your healthcare practitioner about the results if you don't hear back to ensure that the tests were done and that results were normal. If the results indicate that further testing is needed, your baby's healthcare practitioner will notify you as soon as possible.

If your baby does need further testing, your healthcare practitioner or program coordinator will contact you and tell you what needs to be done next. Additional testing does not necessarily mean that your baby is sick, just that more tests are needed to ensure there is not a problem. If follow-up tests are needed, they should be done as soon as possible in case your baby does need prompt treatment.

Below is a table summarizing the 34 core disorders for which the Secretary's Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC) recommends newborns be screened as of November 2016.

Screening tests for certain inherited diseases that are not already covered by mandatory statewide screening may be requested based on family history or ethnic background. Testing typically involves detecting the specific gene mutation(s), or change in DNA, associated with a disorder that occurs frequently within a family or members of a specific ethnic group. Parents may decide to ask for supplemental tests for their newborn in these situations:

Family history: When parents are concerned that a certain disease runs in their families (e.g., Duchenne muscular dystrophy, fragile X syndrome, or other chromosomal abnormalities), they may request that their newborn be tested for the disease. While testing for cystic fibrosis may be ordered because of family history, for example, its frequency in the population at large means that testing is now recommended for all newborns. Every state's newborn screening program includes a test for CF, although the method used may vary, with some states performing only a test to determine the blood level of a chemical called immunoreactive trypsinogen (IRT) and others performing both an IRT and a DNA test to check for mutations or changes in the CF gene.

Ethnic group: When parents are concerned because a certain disorder is common among their ethnic groups (e.g., Tay-Sachs disease, thalassemia, sickle cell anemia, cystic fibrosis, or congenital adrenal hyperplasia (CAH)), they may request that their newborn be tested. Again, several of these disorders are already included in many states' newborn screening programs.

Other risks: Less frequently, some parents request that their newborn's DNA be tested to identify a condition or risk of developing a condition that may not become evident or have an effect until later in life (e.g., Huntington disease, type 1 diabetes, and some forms of breast, ovarian, and colon cancer). Some parents value the information and want to be on the lookout for improvements in diagnosis, prevention, and treatment.

Genetic tests can be run on blood, other types of body fluids, and tissues. For some conditions, chromosomes are examined for abnormalities; for other diseases, a single gene is analyzed. It should be noted that some genetic tests will identify a condition for which there is no treatment or cure and no changes can be made to improve the child's quality of life. The value of such test results is controversial.

Typically, newborns are tested for infectious diseases only if they show signs and symptoms. Currently, asymptomatic newborns may be screened for two infectious diseases: HIV or hepatitis B. Usually these screening tests are only performed if it is known that the mother has the disease or if she was not tested during the pregnancy and therefore her disease status is unknown. Some states mandate HIV testing of all newborns. Though the newborns may show no signs or symptoms of infection, they may have contracted the disease during the pregnancy or birth. Treatment can be administered soon after birth to protect the health of the newborn.

Human immunodeficiency virus (HIV) is the virus that causes AIDS (acquired immunodeficiency syndrome). The infection can pass from an infected mother to her child during pregnancy, delivery, or breastfeeding (see HIV Screening during Pregnancy).

Most AIDS cases in children in the United States result from mother-to-baby transmission. If a mother with HIV does not receive treatment during the pregnancy, the child has a 1 in 4 chance of getting HIV. With timely treatment, however, fewer than 2% of children of infected mothers get the virus.

Thanks to aggressive screening and early intervention, the United States has seen a steady decline in new AIDS cases in children. The best way to protect the child's health is to detect the HIV infection as early as possible during pregnancy (or before a woman gets pregnant), treat the mother with medication, and make birthing plans to help the baby avoid infection (such as a C-section rather than vaginal birth).

If the mother was not tested during the pregnancy or at the time of the delivery, the newborn can be screened and, if positive, treated shortly after birth. HIV testing has become routine prenatal care in this country; some states even require that all pregnant women or their newborns be tested.

Screening the mother: All pregnant women in the United States should be counseled about HIV early in their pregnancy and receive voluntary HIV testing to protect the child's health. This is the recommendation of many groups, including the Centers for Disease Control and Prevention, American Academy of Pediatrics, American College of Obstetricians and Gynecologists, and U.S. Preventive Services Task Force. Women who are at high risk for HIV should be tested again in the third trimester.

Screening the baby: In the United States, if the mother's HIV status is not determined before or during pregnancy or during labor and delivery, healthcare practitioners recommend that the newborn be given an HIV test (see FAQ #4 here). In a few states, this is a requirement. Treatment begun quickly after birth can help to prevent a baby who was exposed to the virus from becoming infected.

Treatment of HIV-infected mothers during pregnancy, precautions at birth, and avoiding breast-feeding can minimize the risk of passing the infection from mother to child. Giving the antiretroviral drug zidovudine intravenously during labor and delivery and also to the newborn twice a day by mouth for 6 weeks reduces the rate of transmission from 25-33% to about 1-2%. A combination of antiretroviral therapies is most effective at reducing the risk of HIV transmission to the baby.

It is recommended that all pregnant woman be screened for hepatitis B infections either before or early in her pregnancy regardless of previous hepatitis B vaccination or previous negative hepatitis B (HBsAg) test result. Women at increased risk of hepatitis B infection, such as those with intravenous drug use, should be screened again at delivery. Infection with the hepatitis B virus causes an inflammation of the liver.

It is important to detect active hepatitis B infections in pregnant women because newborns are especially vulnerable to developing chronic infection, which can over the course of many years cause progressive liver damage. If a hepatitis infection is detected in a pregnant woman, she can be monitored and the baby can receive treatment at birth to minimize the risk of developing hepatitis B. Without treatment, about 40% of babies born to mothers infected with hepatitis B develop chronic hepatitis.

With the advent of screening pregnant women for hepatitis B and the vaccination of newborns, the number of infected babies has fallen. However, a newborn may be screened if there is concern that the mother is at high risk of infection and/or she was not tested during the pregnancy.

(November 2013) American College of Obstetricians and Gynecologists. Frequently Asked Questions Pregnancy. Available online at http://www.acog.org/~/media/For%20Patients/faq093.pdf. Accessed April 2017.

(November 2013) American College of Obstetricians and Gynecologists. Frequently Asked Questions Pregnancy. Available online at http://www.acog.org/~/media/For%20Patients/faq093.pdf. Accessed April 2017.

(2016 March 23). HIV among pregnant women, infants, and children. Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/hiv/group/gender/pregnantwomen/index.html. Accessed April 2017.

(Updated 2016 August 22). Screening recommendations and considerations referenced in treatment guidelines and original sources. Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/std/tg2015/screening-recommendations.htm. Accessed April 2017.

(2016 October 4). Viral hepatitis: Perinatal transmission. Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/hepatitis/hbv/perinatalxmtn.htm. Accessed April 2017.